Anti-offset powder distributor



Sept. 27, 1966 R. c. wARczAK ANTI-OFFSET POWDER DISTRIBUTOR 2 Sheets-Sheet 1 Filed July 1, 1964 Sept. 27, 1966 R. c. wARczAK 3,275,196

ANTI-OFFSET POWDER DISTRIBUTOR Filed July l, 1964 2 Sheets-Sheet 2 A ji/Za/efzZv/ 23 is'eZZ Cf Ward av United States Patent O 3,275,196 ANTI-GFFSET POWDER DISTRIBUTOR yRussell C. Warczak, Chicago, lll., assignor to Intercompany Corporation, a corporation of Illinois Filed July 1, 1964, Ser. No. 379,637 13 Claims. (Cl. 222-193) This invention relates to an anti-offset powder distributor for printing presses.

The use of fine powder as an offset preventing means in printing is an extremely old expedient, and it has long been recognized that satisfactory results depend on reliability and uniformity of distribution of thepowder on the wet side of the newly printed sheets as Well as upon the application of the very minimum amount of powder to the printed surface.

In prior uses of Ian anti-offset powder on the printed output of high speed commercial presses the powder has usually been taken from a common source by flowing air which separates and entrains the powder and this air has then 'been directed through hoses or air conduits to discharge points where the air and its entrained powder was directed onto the surface of the moving sheet. In other instances the powder in a supply trough was separated by a rotating brush and then dropped or carried by an air current onto the surface of the printed sheet.

Such prior distributors have been unsatisfactory in that accuracy or completeness of distribution and uniform and accurate feed rates could not be attained with any degree of reliability. Moreover, with prior devices, gradual variation of the feed rate could not lbe attained nor could the feed rate be reduced to a point where the very minimum of powder would be applied to the printed sheets.

The primary object of this invention is to simplify the attainment of reliable and uniform distribution of the anti-offset powder on printed sheets being delivered at high speed by a printing press, and objects related to the foregoing are to enable airborne delivery of anti-offset powder to -be attained in such a way that luniformity of distribution is inherently attained, and to enable the delivery trate of the powder to be readily varied to meet requirements.

Another and more specific object of the invention is to enable uniform delivery and distribution of anti-offset powder to be attained by means that are compact and of such a character that such means may be mounted in the confined or limited space available on a printing press, and a related object is to provide apparatus for this purpose that basically constitutes a bridge structure adapted to bridge the side frames of a press.

Another import-ant object of this invention is to provide anti-offset apparatus wherein the powder is initially distributed in a confined relation across the entire span of the delivery end of a press and is withdrawn in a uniform manner by iiowing air from a plurality of delivery openings spaced uniformly across the span for subsequent discharge with the flowing air onto the printed sheets delivered by the press.

Other and further objects of the present invention will be apparent from the following description and claims, 'and are illustrated in the accompanying drawings, which, lluy way of illustration, show a preferred embodiment of the present invention `and the principles thereof, and what is now considered to be the best mode in which to apply these principles. Other embodiments of the invention embodying the same or equivalent principles may be yused and structural changes may .be made as desired by those skilled in the art without departing Ifrom the invention.

In the drawings:

3,275,196 Patented Sept. 27, 1966 ICC FIG. l is a fragmentary elevation-al view of an antioffset powder distributor employing the features of the invention;

FIG. 2 is a fragmentary longitudinal sectional view through the distributing conveyor of the apparatus;

FIG. 3 is an e-nd view taken from the left in FIG. l;

FIG. 4 is an enlarged vertical sectional view taken substantially along the line 4-4 of FIG. 1; and

FIG. S is a schematic view showing the location of the present apparatus with respect to :the delivery end of a high speed printing press.

For purposes of disclosure the invention is herein illustrated as embodied in an anti-offset powder ldistributing apparatus 10 that has an elongated and relatively narrow bridge structure 11 extended between the side frames 12 of a printing press at the delivery end thereof so that anti-offset powder may be deposited uniformly across the width of the sheets S, FIG. 5, that are transported in succession and deposited Iupon the stack P of printed sheets. In FIG. 5 a diagrammatic representation of the delivery end of the press has been shown with the sheets S advancing on the impression cylinder 14 and then being transferred from the grippers of the impression cylinder to the grippers 1S of a conventional delivery -conveyor 16. As will be evident in FIG. 5, the -unit 10 of the present invention is of such a character that it may be mounted between the runs of the delivering conveyor 16 and may be located in a relatively remote relationship with respect to the impression cylinder 14 and relatively close to the final delivery position where the sheets S` are deposited in succession on the pile or stack P.

The unit 10 is so constructed and arranged under the present invention that most of the physical structure of the unit is contained within Iand forms a part of the bridge structure 11, and in addition to this bridge structure, the unit 10 embodies `a powder supply hopper 18 disposed outside of one of the side frames 12. Powder from the supply hopper 18 is distributed mechanically throughout the entire span of the bridge structure 11 by a conveyor 20 that extends entirely through the bridge structure 11 and outwardly beyond the other side frame 12 where excess powder that may be fed by the conveyor 20 is deposited in a closed glass-walled collecting container 22.

The screw conveyor 20 thus provides a continuous and uniform body .of powder extending entirely across the length of and within the bridge structure 11 and under and -in accordance with the present invention, rapidly flowing air is caused t-o withdraw powder at a uniform rate from a plurality of closely spaced points along the conveyor 20 and to carry the withdrawn powder along a confined path within and laterally of the bridge structure for final discharge onto a moving sheet S through a plurality of closely spaced powder exit openings 23, as will now be described in detail.

The bridge structure 11 is provided by concentric inner and .outer tubes 24 and 26 that have the length necessary to span the width of the sheets S that are being printed, and at their ends, the inner and outer tubes 24 and 26 have their walls 27 and 28 welded thereto so that the inner tube 24 defines a closed inner cylindrical chamber 29, while the space between the inner tube 24 and the outer tube 26 defines an annular chamber 30. Angle brackets 31 welded to the respective end Walls 27 and 28 and adapted to rest upon and be bolted to brackets 12B on the inner surfaces of the side frames 12, thus to provide a convenient mounting for the bridge structure.

The conveyor 20 is provided by a relatively small diameter auger tube 32 that has a spiral spring 33 extended therethrough in a rotatable relationship so that it may serve as a ribbon type auger for advancing powder longitudinally of the auger tube 32. The auger tube 32 is extended in a suitable sealed relation through the opposite end walls 27 and 28, and at its left hand end as viewed in FIG. l the auger tube extends entirely through the bottom of the hopper 18 and has an opening 32S through which powder in the hopper 18 may enter the auger 32 by gravity. At the left hand side of the supply hopper 18, as viewed in FIG. 1, the auger engages and is fixed to a drive shaft 33 as shown in FIG. 2, and this drive shaft extends through a sealed bearing 34 at the end of the auger tube and is connected through a coupling 35 with a motor driven variable speed drive 36. The drive 36 is supported by a lbracket 36B on the side frame 12. Powder entering the opening 32S -is distributed or fed to the right through the auger tube 32 by the action of the auger 33, and at the right hand end of the unit 10, the auger tube 32 extends through the side frame 12 and is connected to a tting 3S which carries the receiving jar 22 in a sealed relationship for purposes that will appear hereinafter.

The auger tube 32 is utilized as mechanical means for distributing powder uniformly across the width of the bridge structure 11, and this powder may be withdrawn from the bottom of the auger tube 32 through uniformly spaced discharge openings 40 formed in the auger tube. Such withdrawing of powder from the auger tube 32 is accomplished under the present invention in such a way that the rate of withdrawal of the powder may be accurately controlled and may be va-ried according to the requirements presented. Thus, an air supply manifold 50 from which air is discharged, as will :be described, is mounted so as to extend throughout the entire length of the chamber 29 and through the end walls 27 and 28, and the exposed opposite end-s of the manifold 501 are closed and have pipe fittings 51 associated therewith. These pipe fittings 51 have compressed air connections thereto, the compressed air being supplied through a line 52, an adjustable pressure-reducing valve 53 and branch lines 54 extended from the pressure reducing valve 53 lto the end fittings 51. The air pressure within the manifold 50 is Variable of course by the adjustment of the pressure reducing valve 53 and such pressure is usually established in the neighborhood of 20 pounds per square in-ch.

The manifold 50 and the auger tube 32 are spaced from opposite sides of the inner chamber 29 and from each other, as shown in FIG. 4 so as to enable air to circulate within the inner chamber, as will be described.

Air is discharged from the manifold 50 in the form .of jets from a series of closely and uniformly spaced openings 55 formed throughout the length of the manifold 50, and as will be evident particularly in FIG. 4, these openings 55 are arranged so as to discharge the air upwardly so that it will flow in a generally circular path across the top of the chamber 29, and then downwardly about both sides of the auger tube 32, and this causes the air howing past the both sides of the auger tube 32 to exert an aspirating action on the openings 40. This aspirating action serves to withdraw powder from the several openings 40 so that the powder flows downwardly into the air stream as indicated at 56 in FIG. 4, and the powder is thus entrained in the moving air so as to continue in a counterclockwise movement as shown by the arrows in FIG. 4. As the air with its entrained powder reaches the right hand side of the inner tube 24, as shown in FIG. 4, the air and the entrained powder passes through a plurality of openings 60 that are formed in the inner tube 24. These openings 6d are disposed at an angle such that the entrained air and powder may enter into the annular chamber 30. The air and the entrained powder then continue their generally circular movement within the annula-r chamber 30 as indicated by the arrows in FIG. 4, and some additional air is introduced through the openings 60A, FIG. 4, as `this air ows from the initial discharge openings 55. The air and the entrained powder .continue the flow through the annular chamber 30 to the series of final exit -or discharge openings23 that are evenly spaced along the lower edge of the outer tube 26 as shown in FIGS. 1 and 4. Thus the air and the entrained powder are discharged through the openings 23 so as to be directed to the newly printed surface of the advancing sheets S, as indicated in FIG. 5 of the drawings.

Since the powder within the auger tube 32 is of such a character it has a more or less normal tendency to arch over a bottom discharge openings 40, it is found that the application of an aspirating action t-o the discharge openings 4tl constitutes the major factor in withdrawing the powder at a uniform rate from the openings 40. The aspirating action of the moving air is uniform throughout the length of the inner chamber 29, and as a result the powder is withdrawn uniformly from the respective openings 40 and the uniform supply of powder that is provided throughout the entire length of the auger tube 32. The powder that is thus withdrawn is subjected to a uniform blast of air that moves generally perpendicular to the axis of the inner tube 24 and which tends to break up and separate the powder as it moves toward the several openings 60. Then as the air and the powder move through and into the `annular chamber 30, a further opportunity for separation and distribution of the powder is provided throughout the relatively long path within the annular chamber. Hence when the air is finally discharged from the uniformly spaced opening 23, there is a uniform distribution of the discharge powder throughout the entire length of the outer tube 26 and uniform distribution over the surface of the advancing sheet S.

It has been pointed out that it is desirable to be able to accurately vary and regulate the discharge rate of powder from the conveyor openings 40, and under the present invention this is readily accomplished by varying the air pressure within the manifold 50, this being accomplished by adjustment of the pressure regulating valve 53.

It should be understood that where the rate of discharge of powder from the openings 40 is varied, there must necessarily be a corresponding adjustment of the rate of supply powder to the auger tube 32. This is accomplished by varying the speed of the auger 33, and it is desirable to regulate the supply rate of powder so that just enough powder is fed into the auger tube 32 to replace the powder that is withdrawn by air aspirating action from the several discharge openings 40. Thus, with the present structure, after setting the air pressure to the desired value, the feed rate of the conveyor 20 may be adjusted readily and easily so that at all times there will be a slight overfeeding action with the excess material being discharged in a visible relation into the collecting container 22. It is again noted that the collecting container 22 is closed, and lthis is an important factor because the aspirating action that is exerted on the openings 40 of the auger tube would normally tend to draw air into the terminal end of the auger tube 32 so as to disturb the uniformity of the feeding movement applied to the powder within the auger tube.

The study and compact character of the present apparatus is of particular note, and as an example, it may be pointed out that where the width o-f the press requires an bridge structure, it is possible to use a 5 diameter outer tube 26, a 4%" inner tube 24, a manifold 50 of 11/16" diameter, and 'an auger tube of 11/16 diameter, the various openings 23, 40, 55 and 60 being of W16 diameter in each case. The tubes that are thus employed impart sufficient strength so that they are self supporting throughout .their entire length, and the maximum diameter of 5 that has been used in this instance for the outer tube 26 enables the unit to he fitted in relatively close structural relationship to the parts of the press, as is shown in FIG. 5 of the drawings.

It has 4been found that with the present application the feed rate is uniform and may be varied at will to meet the requirements presented by a particular printing job. Moreover, it is found that the powder, after being initially distributed across the width of the press by mechanical means, is then withdrawn uniformly by the action of the Iair jets within the inner tube so that the supply rate of distribution of powder to the air that is thereafter to carry the powder to its point of use is uniform. Furthermore, the powder that has .thus been uniformly drawn into the inner tube is thereafter subjected to the action of the flowing air in such a way that the powder is broken up and uniformly distributed so that it may then be uniformly discharged from the several exit openings 23 onto the printed sheet.

From the foregoing description it will be apparent that the present invention enables proper and uniform distribution of anti-offset powder to be readily and easily attained, and it will further be apparent that the uniform rate of delivery of powder may be changed and regulated according to the situation that is encountered.

Thus while a preferred embodiment of the present invention has been illustrated, it is to be understood that changes and variations may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim:

1. In an anti-offset powder distributor for printing presses, a bridge structure adapted to be mounted transversely across and adjacent .to the path of advancing sheets issuing in succession from a delivery end of a printing press, said bridge structure comprising concentric inner and outer tubes having end walls closing adjacent ends of the tubes to dene a cylindrical inner chamber within the inner tube and an outer annular charnber between said tubes, powder supply and delivery means comprising a relatively small diameter auger tube extended longitudinally through said inner chamber and through said end walls, a rotatable auger in said auger tube, a supply hopper discharging into one end of the auger tube for feeding powder into said one end of the auger tube, variable speed drive means for rotating said auger to advance powder longitudinally of the auger tube to the other end thereof, a closed collecting container at the other end of the tube into which excess powder may be discharged, said auger tube having bottom discharge openings therein at points spaced uniformly longitudinally of the auger tube and through which powder may be discharged into said inner chamber, an air supply header located within said inner chamber and extended throughout the length thereof and having uniformly spaced air discharge openings therein for discharging air tangentially with respect to said cylindrical chamber, means for supplying air to said air supply header including means for Varying the pressure of the air supply to the header, said inner tube having air discharge openings therein spaced uniformly along said tube for discharging air and powder from the inner chamber into said lannular chamber in a direction circumferentially of said annular chamber, and said outer tube having tinal discharge openings formed in equally spaced relation throughout its length through which air may carry and discharge powder uniformly onto .an advancing printed sheet.

2. An anti-offset powder distributor according to claim 1 wherein said auger tube and said header have their axes disposed substantially in a common horizontal plane and wherein the spaced air discharge openings in said header direct the issuing air Igenerally across the top of the inner tube and toward the auger tube.

3. An anti-offset powder distributor according to claim 1 wherein said auger tube and said header have their axes disposed substantially in a common horizontalplane and wherein the spaced air discharge openings in said header direct the issuing air generally across the top of the inner tube and toward the auger tube, and in which the discharge openings in said inner tube are in a plurality of rows at least one row of which is arranged in the path of a portion of the air issuing from air discharge openings of said header.

4. An anti-offset powder distributor according to claim 1 wherein air is supplied at the same pressure to opposite ends of said header.

5. An anti-offset powder distributor according to claim 1 wherein the discharge openings in the inner and outer tubes are arranged at a small acute angle to the path of movement Iof air that is to pass therethrough.

6. An anti-offset powder distributor according to claim 1 wherein said auger tube and said header are disposed on opposite sides of the axis of said inner tube and in which the openings in the header discharge air in a direction such that this air passes around the auger tube and applies an aspirating action to the bottom discharge openings of the auger tube to withdraw powder therefrom.

7. In an anti-offset powder distributor for printing presses, a bridge structure adapted to be mounted transversely across and adjacent to the path of .advancing sheets issuing in succession from a delivery end of a printing press, powder supply means carried by said bridge structure and having a row of identical uniformly spaced powder dispensing openings arranged across the span of said bridge structure, means for directing air past all of said dispensing openings with a uniform aspirating action to Withdraw powder from said dispensing openings, means for varying the aspirating action of said air, and means defining an enclosed path terminating in uniformly spaced delivery openings through which such air and the entrained powder are discharged in a uniformly distributed relation across the entire span of said bridge structure.

8. In an anti-offset powder distributor rfor printing presses, a bridge structure adapted to be mounted transversely across and adjacent to the path of advancing sheets issuing in succession from a delivery end of a printing press, powder supply means carried by said bridge structure and including a conveyor having a row of identical uniformly spaced powder dispensing openings arranged across the span of said 'bridge structure, means for directing air past all of said dispensing openings with a uniform aspirating action to withdraw powder from said :dispensing openings, means for varying the conveying action of the conveyor, means for varying the aspirating action of said air, and means defining an enclosed path terminating in uniformly spaced delivery openings through which such air and the entrained powder are discharged in a uniformly distributed relation across the entire span of said bridge structure.

9. In an anti-offset powder distributor for printing presses, a bridge structure adapted to be mounted transversely across and adjacent to the path of advancing sheets issuing in succession from a delivery end of a printing press, means having spaced dispensing openings carried by said bridge structure for mechanically distributing powder across the span of the bridge structure, means for directing air past said dispensing openings with an aspirating effect to Withdraw powder from said dispensing openings and entrain said powder in said `air, means for varying said aspirating effect, and means defining an enclosed path terminating in uniformly spaced delivery openings through which such air and the entrained powder are discharged in a uniformly distributed relation across the entire span of said bridge structure.

10. In an anti-offset powder distributor for printing presses as defined in claim 9 wherein the means for withdrawing powder is provided by jets of compressed air at spaced points across the bridge structure.

11. In an anti-offset powder distributor for printing presses as defined in claim 9 wherein the means for mechanically distributing powder comprises an elongated auger tube with uniformly spaced bottom discharge openings and having an langer therein, together with a supply hopper feeding the auger tube at one end and a closed receptacle at the orher end of the auger tube to receive excess powder fed through the tube.

'12. In an anti-offset powder distributor for printing presses as `dened in lclaim 9 wherein the means for mechanically distributing powder comprises Ian elongated auger tube with uniformly spaiced bottom discharge lopenings and having an auger therein, together with a supply hopper feeding the auger tube at one end and a closed receptable at the other end of the auger tube to receive excess powder fed through the tube, fand wherein said withdrawing means is provided by jets of air passing said bottom openings with an aspirating action.

13. In an anti-v'offset powder distributor for printing presses as defined in claim 9 wherein the enclosed path is uniform across the Width of the bridge structure and causes flow of the air perpendicular to the length of such structure.

References Cited by the Examiner UNITED STATES PATENTS Bishop 118-308 X Langdon 118-308 X Thompson 118-308 Daniels.

Wil-helm 118--308 X ROBERT E. PULFREY, Primary Examiner.

DAVID KLEIN, Examiner. H. P. EWELL, Assistant Examiner. 

9. IN AN ANTI-OFFSET POWDER DISTRIBUTOR FOR PRINTING PRESSES, A BRIDGE STRUCTURE ADAPTED TO BE MOUNTED TRANSVERSELY ACROSS AND ADJACENT TO THE PATH OF ADVANCING SHEETS ISSUING IN SUCCESSION FROM A DELIVERY END OF A PRINTING PRESS, MEANS HAVING SPACED DISPENSING OPENINGS CARRIED BY SAID BRIDGE STRUCTURE FOR MECHANICALLY DISTRIBUTING POWDER ACROSS THE SPAN OF THE BRIDGE STRUCTURE, MEANS FOR DIRECTING AIR PAST SAID DISPENSING OPENINGS WITH AN ASPIRATING EFFECT TO WITHDRAW POWDER FROM SAID DISPENSING OPENINGS AND ENTRAIN SAID POWDER IN SAID AIR, MEANS FOR VARYING SAID ASPIRATING EFFECT, AND MEANS DEFINING AN ENCLOSED PATH TERMINATING IN UNIFORMLY SPACED DELIVERY OPENINGS THROUGH WHICH SUCH AIR AND THE ENTRAINED POWDER ARE DISCHARGED IN A UNIFORMLY DISTRIBUTED RELATION ACROSS THE ENTIRE SPAN OF SAID BRIDGE STRUCTURE. 